Integrated circuit and radio-frequency module

ABSTRACT

An integrated circuit includes a first base that has at least a part formed of a first semiconductor material and that includes an electric circuit (for example, a control circuit or a switching circuit), a second base that has at least a part formed of a second semiconductor material having a thermal conductivity lower than the first semiconductor material and that includes a power amplifier circuit, and a low thermal conductive member that has at least a part formed of a low thermal conductive material having a thermal conductivity lower than the second semiconductor material and that is disposed between the electric circuit and the power amplifier circuit. At least a part of the first base overlaps at least a part of the second base in plan view.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of International Application No.PCT/JP2021/041934 filed on Nov. 15, 2021 which claims priority fromJapanese Patent Application No. 2020-200424 filed on Dec. 2, 2020. Thecontents of these applications are incorporated herein by reference intheir entireties.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

The present disclosure relates to an integrated circuit and aradio-frequency module.

Description of the Related Art

Mobile communication devices such as a cellular phone have morecomplicated arrangement configurations of circuit devices, which areincluded in radio-frequency front-end circuits, particularly withadvances in multiband technology.

The radio-frequency module described in Patent Document 1 achieves areduction in size of the radio-frequency module by stacking controllersabove power amplifiers disposed on a packaging substrate.

Patent Document 1: U.S. Pat. Application Publication No. 2017/0338847

BRIEF SUMMARY OF THE DISCLOSURE

However, in the related art described above, the electric circuits (thecontrollers) stacked above the power amplifiers may be heated due to theheat generated by the power amplifiers, resulting in the degradation ofthe characteristics of the electric circuits.

Accordingly, the present disclosure provides an integrated circuit and aradio-frequency module which achieve contribution to a reduction in sizeof the radio-frequency module and which achieve the suppression of thedegradation of the characteristics of electric circuits due to the heat.

An integrated circuit according to an aspect of the present disclosureincludes a first base that has at least a part formed of a firstsemiconductor material and that includes an electric circuit, a secondbase that has at least a part formed of a second semiconductor materialhaving a thermal conductivity lower than the first semiconductormaterial and that includes a power amplifier circuit, and a low thermalconductive member that has at least a part formed of a low thermalconductive material having a thermal conductivity lower than the secondsemiconductor material and that is disposed between the electric circuitand the power amplifier circuit. At least a part of the first baseoverlaps at least a part of the second base in plan view.

An integrated circuit according to an aspect of the present disclosureincludes a first base that has at least a part formed of silicon orgallium nitride and that includes an electric circuit, a second basethat has at least a part formed of gallium arsenide or silicon germaniumand that includes a power amplifier circuit, and a low thermalconductive member that has at least a part formed of glass or epoxyresin and that is disposed between the electric circuit and the poweramplifier circuit. At least a part of the first base overlaps at least apart of the second base in plan view.

An integrated circuit according to an aspect of the present disclosureincludes a first base that has at least a part formed of a firstsemiconductor material and that includes an electric circuit, and asecond base that has at least a part formed of a second semiconductormaterial having a thermal conductivity lower than the firstsemiconductor material and that includes a power amplifier circuit. Ahollow space is formed inside the first base. The hollow space islocated between the electric circuit and the power amplifier circuit. Atleast a part of the first base overlaps at least a part of the secondbase in plan view.

An integrated circuit according to an aspect of the present disclosureincludes a first base that has at least a part formed of silicon orgallium nitride and that includes an electric circuit, and a second basethat has at least a part formed of gallium arsenide or silicon germaniumand that includes a power amplifier circuit. A hollow space is formedinside the first base. The hollow space is located between the electriccircuit and the power amplifier circuit. At least a part of the firstbase overlaps at least a part of the second base in plan view.

The integrated circuit according to an aspect of the present disclosureachieves the contribution to a reduction in size of a radio-frequencymodule and achieves the suppression of the degradation of thecharacteristics of a power amplifier circuit due to the heat.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a diagram illustrating the circuit configuration of aradio-frequency module and a communication device according to anembodiment.

FIG. 2 is a plan view of a radio-frequency module according to anembodiment.

FIG. 3 is a cross-sectional view of a radio-frequency module accordingto an embodiment.

FIG. 4 is a partial cross-sectional view of a radio-frequency moduleaccording to an embodiment.

FIG. 5 is a partial cross-sectional view of a radio-frequency moduleaccording to an embodiment.

FIG. 6 is a diagram illustrating the circuit layout in an integratedcircuit according to an embodiment.

FIG. 7 is a partial cross-sectional view of a radio-frequency moduleaccording to a modified example of an embodiment.

DETAILED DESCRIPTION OF THE DISCLOSURE

Embodiments of the present disclosure will be described below in detailby using the drawings. Each embodiment described below is acomprehensive or concrete example. The numeral values, the shapes, thematerials, the components, the layout and the connection form ofcomponents, and the like described in the embodiments described beloware exemplary, and are not intended to limit the present disclosure.

The figures are schematic views with appropriate emphasis, abbreviation,or adjustment of ratios for illustration of the present disclosure, andare not necessarily illustrated strictly. The shapes, the positionalrelationship, and the ratios may be different from the actual ones. Inthe figures, substantially the same configurations are designated withthe same reference numerals. Repeated description may be skipped orsimplified.

In the figures described below, x axis and y axis are orthogonal to eachother in a plane parallel to a principal surface of a module substrate.Specifically, when a module substrate is rectangular in plan view, xaxis is parallel to a first side of the module substrate; y axis isparallel to a second side orthogonal to the first side of the modulesubstrate. In addition, z axis is perpendicular to the principal surfaceof the module substrate. The positive direction of z axis indicates theupward direction; its negative direction indicates the downwarddirection.

In a circuit configuration in the present disclosure, “to be connected”encompasses, not only the case of direct connection using a connectionterminal and/or a wiring conductor, but also the case of electricalconnection via other circuit devices. “To be connected between A and B”means connection, between A and B, to both A and B.

In a component layout in the present disclosure, “in plan view” meansviewing an object subjected to orthogonal projection to the xy planefrom the z-axis positive side. “In plan view, A overlaps B” means thatthe area of A subjected to orthogonal projection to the xy planeoverlaps the area of B subjected to orthogonal projection to the xyplane. “In cross-sectional view” means viewing a cross section which isperpendicular to the xy plane and which is obtained through cutting. “Incross-sectional view, A is disposed between B and C” means that, in across section perpendicular to the xy plane, at least one of linesegments connecting any points in the area of B to any points in thearea of C passes through the area of A. “A is disposed between B and C”means that at least one of line segments connecting any points in thearea of B to any points in the area of C passes through A. Termsindicating the relationships between components, such as “parallel” and“perpendicular”, terms indicating the shapes of components, such as“rectangular”, and numeral ranges are not intended to have only strictmeaning, and mean substantially equivalent ranges, for example, havingerrors in the order of a few percent.

In addition to placement of a component on a substrate in the state inwhich the component is in contact with the substrate, “to dispose acomponent on/in a substrate” encompasses placement of a component abovea substrate in the state in which the component is not in contact withthe substrate (for example, the component is laminated on anothercomponent disposed on the substrate), and placement of a component inthe state in which a part or the entirety of the component is embeddedin the substrate. In addition to placement of a component on a principalsurface of a substrate in the state in which the component is in contactwith the principal surface, “to dispose a component on a principalsurface of a substrate” encompasses placement of a component above aprincipal surface in the state in which the component is not in contactwith the principal surface, and placement of a component in the state inwhich a part of the component is embedded in a substrate from theprincipal surface side.

In a material composition described in the present disclosure, “object Ais formed of material B” means that the main component of A is B. Themain component means a component having the largest weight ratio amongthe multiple components contained by an object.

Embodiment 1.1 The Circuit Configuration of a Radio-Frequency Module 1and a Communication Device 5

The circuit configuration, according to the present embodiment, of aradio-frequency module 1 and a communication device 5, which includesthe radio-frequency module 1, will be described by referring to FIG. 1 .FIG. 1 is a diagram illustrating the circuit configuration of theradio-frequency module 1 and the communication device 5 according to theembodiment.

1.1.1 The Circuit Configuration of the Communication Device 5

As illustrated in FIG. 1 , the communication device 5 according to thepresent embodiment includes the radio-frequency module 1, an antenna 2,an RFIC (Radio Frequency Integrated Circuit) 3, and a BBIC (BasebandIntegrated Circuit) 4.

The radio-frequency module 1 transports radio-frequency signals betweenthe antenna 2 and the RFIC 3. The internal configuration of theradio-frequency module 1 will be described below.

The antenna 2, which is connected to an antenna connection terminal 100of the radio-frequency module 1, receives radio-frequency signals fromthe outside, and outputs the radio-frequency signals to theradio-frequency module 1.

The RFIC 3 is an exemplary signal processing circuit which processesradio-frequency signals. Specifically, the RFIC 3 performs signalprocessing such as down-converting on radio-frequency receive signalsreceived through the receive paths of the radio-frequency module 1, andoutputs, to the BBIC 4, the receive signals generated through the signalprocessing. In addition, the RFIC 3 has a controller which controls, forexample, switching circuits and amplifier circuits which are included inthe radio-frequency module 1. Some or all of the functions, as acontroller, of the RFIC 3 may be included in a component which ispresent outside the RFIC 3, and may be included, for example, in theBBIC 4 or the radio-frequency module 1.

The BBIC 4 is a baseband signal processing circuit which performs signalprocessing using an intermediate frequency band whose frequency is lowerthan that of radio-frequency signals transported by the radio-frequencymodule 1. Signals processed by the BBIC 4 are, for example, imagesignals for image display and/or voice signals for calls through aspeaker.

In the communication device 5 according to the present embodiment, theantenna 2 and the BBIC 4 are not necessary components.

1.1.2 The Circuit Configuration of the Radio-Frequency Module 1

The circuit configuration of the radio-frequency module 1 will bedescribed. As illustrated in FIG. 1 , the radio-frequency module 1includes a power amplifier circuit 11, a low-noise amplifier circuit 21,impedance matching circuits (MNs) 41 to 44, switching circuits 51 to 55,duplexer circuits 61 and 62, a control circuit 80, the antennaconnection terminal 100, radio-frequency input terminals 111 and 112,radio-frequency output terminals 121 and 122, and a control terminal130.

The antenna connection terminal 100 is connected, outside theradio-frequency module 1, to the antenna 2.

Each of the radio-frequency input terminals 111 and 112 is an inputterminal for receiving radio-frequency transmit signals from the outsideof the radio-frequency module 1. In the present embodiment, theradio-frequency input terminals 111 and 112 are connected, outside theradio-frequency module 1, to the RFIC 3.

Each of the radio-frequency output terminals 121 and 122 is an outputterminal for providing radio-frequency receive signals to the outside ofthe radio-frequency module 1. In the present embodiment, theradio-frequency output terminals 121 and 122 are connected, outside theradio-frequency module 1, to the RFIC 3.

The control terminal 130 is a terminal for transporting a controlsignal. That is, the control terminal 130 is a terminal for receiving acontrol signal from the outside of the radio-frequency module 1, and/ora terminal for supplying a control signal to the outside of theradio-frequency module 1. The control signal is related to the controlof an electronic component included in the radio-frequency module 1.Specifically, the control signal is a digital signal for controlling,for example, the power amplifier circuit 11.

The power amplifier circuit 11 is capable of amplifying transmit signalsin Band A and Band B. The power amplifier circuit 11 is connected, atits input end, to the radio-frequency input terminals 111 and 112through the switching circuit 52. The power amplifier circuit 11 isconnected, at its output end, to transmit-filter circuits 61T and 62Tthrough the impedance matching circuit 41 and the switching circuit 51.

The configuration of the power amplifier circuit 11 is not particularlylimited to this. For example, the power amplifier circuit 11 may be amultistage amplifier circuit, or may be a differential amplifiercircuit.

The low-noise amplifier circuit 21 is capable of amplifying receivesignals in Band A and Band B. The low-noise amplifier circuit 21 isconnected, at its input end, to receive-filter circuits 61R and 62Rthrough the impedance matching circuit 42 and the switching circuit 54.The low-noise amplifier circuit 21 is connected, at its output end, tothe radio-frequency output terminals 121 and 122 through the switchingcircuit 55.

The impedance matching circuit 41 is connected to the output end of thepower amplifier circuit 11, and is connected to the input ends of thetransmit-filter circuits 61T and 62T through the switching circuit 51.The impedance matching circuit 41 is capable of achieving the impedancematching between the output impedance of the power amplifier circuit 11and the input impedance of the switching circuit 51.

The impedance matching circuit 42 is connected to the input end of thelow-noise amplifier circuit 21, and is connected to the output ends ofthe receive-filter circuits 61R and 62R through the switching circuit54. The impedance matching circuit 42 is capable of achieving theimpedance matching between the output impedance of the switching circuit54 and the input impedance of the low-noise amplifier circuit 21.

The impedance matching circuit 43 is connected to the output end of thetransmit-filter circuit 61T and the input end of the receive-filtercircuit 61R, and is connected to the antenna connection terminal 100through the switching circuit 53. The impedance matching circuit 43 iscapable of achieving the impedance matching between the switchingcircuit 53 and the duplexer circuit 61.

The impedance matching circuit 44 is connected to the output end of thetransmit-filter circuit 62T and the input end of the receive-filtercircuit 62R, and is connected to the antenna connection terminal 100through the switching circuit 53. The impedance matching circuit 44 iscapable of achieving the impedance matching between the switchingcircuit 53 and the duplexer circuit 62.

The switching circuit 51, which is an exemplary first switching circuit,is connected between the output end of the power amplifier circuit 11and the input ends of the transmit-filter circuits 61T and 62T. Theswitching circuit 51 has terminals 511 to 513. The terminal 511 isconnected to the output end of the power amplifier circuit 11 throughthe impedance matching circuit 41. The terminal 512 is connected to theinput end of the transmit-filter circuit 61T. The terminal 513 isconnected to the input end of the transmit-filter circuit 62T.

In this connection configuration, the switching circuit 51 is capable ofconnecting the terminal 511 to any of the terminals 512 and 513, forexample, on the basis of a control signal from the RFIC 3. That is, theswitching circuit 51 is capable of switching, between thetransmit-filter circuits 61T and 62T, the connection to the output endof the power amplifier circuit 11. The switching circuit 51 is formed,for example, by using an SPDT (Single-Pole Double-Throw) switch, and maybe called a band select switch.

The switching circuit 52, which is an exemplary second switchingcircuit, is connected between the radio-frequency input terminals 111and 112 and the input end of the power amplifier circuit 11. Theswitching circuit 52 has terminals 521 to 523. The terminal 521 isconnected to the input end of the power amplifier circuit 11. Theterminals 522 and 523 are connected to the radio-frequency inputterminals 111 and 112, respectively.

In this connection configuration, the switching circuit 52 is capable ofconnecting the terminal 521 to any of the terminals 522 and 523, forexample, on the basis of a control signal from the RFIC 3. That is, theswitching circuit 52 is capable of switching, between theradio-frequency input terminals 111 and 112, the connection to the inputend of the power amplifier circuit 11. The switching circuit 52 isformed, for example, by using an SPDT switch, and may be called anin-switch.

The switching circuit 53, which is an exemplary third switching circuit,is connected between the antenna connection terminal 100 and theduplexer circuits 61 and 62. The switching circuit 53 has terminals 531to 533. The terminal 531 is connected to the antenna connection terminal100. The terminal 532 is connected to the output end of thetransmit-filter circuit 61T and the input end of the receive-filtercircuit 61R through the impedance matching circuit 43. The terminal 533is connected to the output end of the transmit-filter circuit 62T andthe input end of the receive-filter circuit 62R through the impedancematching circuit 44.

In this connection configuration, the switching circuit 53 is capable ofconnecting the terminal 531 to one or both of the terminals 532 and 533,for example, on the basis of a control signal from the RFIC 3. That is,the switching circuit 53 is capable of switching between the connectionand the disconnection between the antenna connection terminal 100 andthe duplexer circuit 61, and is capable of switching between theconnection and the disconnection between the antenna connection terminal100 and the duplexer circuit 62. The switching circuit 53 is formed, forexample, by using a multi-connection switch, and may be called anantenna switch.

The switching circuit 54 is connected between the input end of thelow-noise amplifier circuit 21 and the output ends of the receive-filtercircuits 61R and 62R. The switching circuit 54 has terminals 541 to 543.The terminal 541 is connected to the input end of the low-noiseamplifier circuit 21 through the impedance matching circuit 42. Theterminal 542 is connected to the output end of the receive-filtercircuit 61R. The terminal 543 is connected to the output end of thereceive-filter circuit 62R.

In this connection configuration, the switching circuit 54 is capable ofconnecting the terminal 541 to any of the terminals 542 and 543, forexample, on the basis of a control signal from the RFIC 3. That is, theswitching circuit 54 is capable of switching, between the receive-filtercircuits 61R and 62R, the connection to the input end of the low-noiseamplifier circuit 21. The switching circuit 54 is formed, for example,by using an SPDT switch.

The switching circuit 55 is connected between the radio-frequency outputterminals 121 and 122 and the output end of the low-noise amplifiercircuit 21. The switching circuit 55 has terminals 551 to 553. Theterminal 551 is connected to the output end of the low-noise amplifiercircuit 21. The terminals 552 and 553 are connected to theradio-frequency output terminals 121 and 122, respectively.

In this connection configuration, the switching circuit 55 is capable ofconnecting the terminal 551 to any of the terminals 552 and 553, forexample, on the basis of a control signal from the RFIC 3. That is, theswitching circuit 55 is capable of switching, between theradio-frequency output terminals 121 and 122, the connection to theoutput end of the low-noise amplifier circuit 21. The switching circuit55 is formed, for example, by using an SPDT switch, and may be called anout-switch.

The duplexer circuit 61 is capable of passing radio-frequency signals inBand A. The duplexer circuit 61 transports transmit signals and receivesignals in Band A by using an FDD (Frequency Division Duplex) system.The duplexer circuit 61 includes the transmit-filter circuit 61T and thereceive-filter circuit 61R.

The transmit-filter circuit 61T (A-Tx) has a passband including theuplink operating band of Band A. Thus, the transmit-filter circuit 61Tis capable of passing transmit signals in Band A. The transmit-filtercircuit 61T is connected between the power amplifier circuit 11 and theantenna connection terminal 100. Specifically, the transmit-filtercircuit 61T is connected, at its input end, to the output end of thepower amplifier circuit 11 through the switching circuit 51 and theimpedance matching circuit 41. In contrast, the transmit-filter circuit61T is connected, at its output end, to the antenna connection terminal100 through the impedance matching circuit 43 and the switching circuit53.

The receive-filter circuit 61R (A-Rx) has a passband including thedownlink operating band of Band A. Thus, the receive-filter circuit 61Ris capable of passing receive signals in Band A. The receive-filtercircuit 61R is connected between the antenna connection terminal 100 andthe low-noise amplifier circuit 21. Specifically, the receive-filtercircuit 61R is connected, at its input end, to the antenna connectionterminal 100 through the impedance matching circuit 43 and the switchingcircuit 53. In contrast, the receive-filter circuit 61R is connected, atits output end, to the low-noise amplifier circuit 21 through theswitching circuit 54 and the impedance matching circuit 42.

The duplexer circuit 62 is capable of passing radio-frequency signals inBand B. The duplexer circuit 62 transports transmit signals and receivesignals in Band B by using an FDD system. The duplexer circuit 62includes the transmit-filter circuit 62T and the receive-filter circuit62R.

The transmit-filter circuit 62T (B-Tx) has a passband including theuplink operating band of Band B. Thus, the transmit-filter circuit 62Tis capable of passing transmit signals in Band B. The transmit-filtercircuit 62T is connected between the power amplifier circuit 11 and theantenna connection terminal 100. Specifically, the transmit-filtercircuit 62T is connected, at its input end, to the output end of thepower amplifier circuit 11 through the switching circuit 51 and theimpedance matching circuit 41. In contrast, the transmit-filter circuit62T is connected, at its output end, to the antenna connection terminal100 through the impedance matching circuit 44 and the switching circuit53.

The receive-filter circuit 62R (B-Rx) has a passband including thedownlink operating band of Band B. Thus, the receive-filter circuit 62Ris capable of passing receive signals in Band B. The receive-filtercircuit 62R is connected between the antenna connection terminal 100 andthe low-noise amplifier circuit 21. Specifically, the receive-filtercircuit 62R is connected, at its input end, to the antenna connectionterminal 100 through the impedance matching circuit 44 and the switchingcircuit 53. In contrast, the receive-filter circuit 62R is connected, atits output end, to the low-noise amplifier circuit 21 through theswitching circuit 54 and the impedance matching circuit 42.

The control circuit 80 is a power amplifier controller which controlsthe power amplifier circuit 11. The control circuit 80 receives acontrol signal from the RFIC 3 through the control terminal 130, andoutputs a control signal to the power amplifier circuit 11.

One or more circuits among the circuits illustrated in FIG. 1 are notnecessarily included in the radio-frequency module 1. For example, theradio-frequency module 1 may have any configuration as long as theradio-frequency module 1 includes at least the power amplifier circuit11 and electric circuits (for example, the control circuit 80 and thelike), and the radio-frequency module 1 does not necessarily include theother circuits.

1.2 The Component Layout of the Radio-Frequency Module 1

An exemplary component layout of the radio-frequency module 1 having theconfiguration described above will be described specifically byreferring to FIGS. 2 and 3 .

FIG. 2 is a plan view of the radio-frequency module 1 according to theembodiment. FIG. 3 is a cross-sectional view of the radio-frequencymodule 1 according to the embodiment. The cross section of theradio-frequency module 1 in FIG. 3 corresponds to the cross sectionalong line iii-iii in FIG. 2 .

In addition to the components included in the circuit illustrated inFIG. 1 , the radio-frequency module 1 further includes a modulesubstrate 90, a resin member 91, a shield electrode layer 92, andmultiple external connection terminals 150. In FIG. 2 , the resin member91 and the shield electrode layer 92 are not illustrated. In FIGS. 2 and3 , wiring connecting, to each other, components disposed on the modulesubstrate 90 is not illustrated.

The module substrate 90 has principal surfaces 90 a and 90 b which areopposite to each other. In the present embodiment, the module substrate90 is rectangular in plan view, but the shape of the module substrate 90is not limited to this. The module substrate 90 may be, for example, anLTCC (Low Temperature Co-fired Ceramics) substrate or an HTCC (HighTemperature Co-fired Ceramics) substrate, which has a layered structureof multiple dielectric layers, a component-embedded substrate, asubstrate having an RDL (Redistribution Layer), or a printed board.However, the module substrate 90 is not limited to these.

Integrated circuits 20 and 70, the impedance matching circuits 41 to 44,the switching circuit 53, and the duplexer circuits 61 and 62 aredisposed on the principal surface 90 a. The principal surface 90 a andthe components on the principal surface 90 a are covered by the resinmember 91.

The integrated circuit 20 includes the low-noise amplifier circuit 21and the switching circuits 54 and 55. The integrated circuit 20 may beformed, for example, by using a CMOS (Complementary Metal OxideSemiconductor), and may be specifically manufactured through a SOI(Silicon on Insulator) process. This enables the integrated circuit 20to be manufactured at a low cost. The integrated circuit 20 may beformed of at least one of the following materials: gallium arsenide;silicon germanium (SiGe); and gallium nitride (GaN). This enables ahigh-quality low-noise amplifier circuit 21 and high-quality switchingcircuits 54 and 55 to be implemented.

The integrated circuit 70 includes a first base 71 and a second base 72.The second base 72 and the first base 71 are laminated in this sequenceon the principal surface 90 a of the module substrate 90. The details ofthe integrated circuit 70 will be described below by using FIGS. 4 to 6.

Each of the impedance matching circuits 41 to 44 includes a matchingdevice. The matching device may be an inductor and/or a capacitor. Eachof the matching devices included in the impedance matching circuits 41to 44 is formed by using an SMD (Surface Mount Device). Some or all ofthe matching devices included in the impedance matching circuits 41 to44 may be formed by using an IPD (Integrated Passive Device).

The switching circuit 53 is formed, for example, by using multipleMOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) which areconnected to each other in series. The number of stages in seriesconnection of the MOSFETs may be any as long as the number is determinedin accordance with a required withstand voltage, and has no particularlimitation.

Each of the duplexer circuits 61 and 62 may be formed, for example, byusing any of a SAW (Surface Acoustic Wave) filter, a BAW (Bulk AcousticWave) filter, an LC resonant filter, and a dielectric filter. Further,the configuration is not limited to these.

The resin member 91 covers the principal surface 90 a and the componentson the principal surface 90 a. The resin member 91 has a function ofensuring the reliability of mechanical strength, moisture resistance,and the like of the components on the principal surface 90 a. The resinmember 91 is not a necessary component.

The shield electrode layer 92, which is, for example, a thin metal filmformed by using a sputtering method, is formed so as to cover the topsurface and the side surfaces of the resin member 91 and the sidesurfaces of the module substrate 90. The shield electrode layer 92 isset to the ground potential, and suppresses the invasion of externalnoise into the components included in the radio-frequency module 1.

The external connection terminals 150 are disposed on the principalsurface 90 b. The external connection terminals 150 include the antennaconnection terminal 100, the radio-frequency input terminals 111 and112, the radio-frequency output terminals 121 and 122, and the controlterminal 130 which are illustrated in FIG. 1 , as well as groundterminals. Each of the external connection terminals 150 is joined, forexample, to an input/output terminal and/or a ground terminal on amother board disposed in the z-axis negative direction of theradio-frequency module 1. The external connection terminals 150 may be,for example, bump electrodes, but the configuration is not limited tothis.

The component layout illustrated in FIGS. 2 and 3 is exemplary, and thelayout is not limited to this. For example, some or all of thecomponents may be disposed on the principal surface 90 b of the modulesubstrate 90. In this case, the principal surface 90 b and thecomponents on the principal surface 90 b may be covered by a resinmember.

1.3 The Configuration of the Integrated Circuit 70

The configuration of the integrated circuit 70 will be described byreferring to FIGS. 4 to 6 . FIGS. 4 and 5 are partial cross-sectionalviews of the radio-frequency module 1 according to the embodiment. FIG.6 is a diagram illustrating the circuit layout in the integrated circuit70 according to the embodiment. Specifically, FIG. 4 is an enlargedcross-sectional view of the integrated circuit 70. FIG. 5 is an enlargedcross-sectional view of the second base 72. FIG. 6 is a perspective planview of the integrated circuit 70. In FIGS. 4 to 6 , not all the wiringand electrodes are illustrated. In FIG. 6 , the broken lines indicatethe outlines of the first base 71, the second base 72, and a low thermalconductive member 73.

As illustrated in FIG. 4 , the integrated circuit 70 includes the firstbase 71, the second base 72, and the low thermal conductive member 73.

1.3.1 The Configuration of the First Base 71

The first base 71 will be described. At least a part of the first base71 is formed of a first semiconductor material. In this example, thefirst semiconductor material is silicon (Si). The first semiconductormaterial is not limited to silicon. For example, the first semiconductormaterial may be a material containing, as the main component, any ofgallium arsenide, aluminum arsenide (AlAs), indium arsenide (InAs),indium phosphide (InP), gallium phosphide (GaP), indium antimonide(InSb), gallium nitride, indium nitride (InN), aluminum nitride (AlN),silicon, germanium (Ge), silicon carbide (SiC), and gallium oxide (III)(Ga₂O₃), or a material containing, as the main component, amulticomponent mixed-crystal material composed of more than one of thesematerials. However, the first semiconductor material is not limited tothese.

The switching circuits 51 and 52 and the control circuit 80 are formedin the first base 71. The electric circuits formed in the first base 71are not limited to the switching circuits 51 and 52 and the controlcircuit 80. For example, only either one or some of the switchingcircuits 51 and 52 and the control circuit 80 may be formed in the firstbase 71. In addition, a control circuit (not illustrated) which controlsthe switching circuit 51 and/or the switching circuit 52 may be formedin the first base 71. In addition, at least one of the impedancematching circuits 41 to 44 may be formed in the first base 71.

As illustrated in FIG. 4 , the first base 71 has surfaces 71 a and 71 bwhich are opposite to each other. The surfaces 71 a and 71 b areexemplary first and second surfaces, respectively. Electrodes 717 aredisposed on the surface 71 b.

The first base 71 includes a silicon substrate 711, a silicon dioxide(SiO₂) layer 712, a silicon layer 713, a silicon dioxide layer 714, anda silicon nitride (SiN) layer 715. The silicon dioxide layer 712, thesilicon layer 713, the silicon dioxide layer 714, and the siliconnitride layer 715 are laminated on the silicon substrate 711 in thissequence.

The silicon substrate 711 is formed, for example, of a silicon singlecrystal, and is used as a support substrate.

The silicon dioxide layer 712 is disposed on the silicon substrate 711,and is used as an insulating layer.

The silicon layer 713 is disposed on the silicon dioxide layer 712, andis used as a device layer. In the cross section in FIG. 4 , multiplecircuit devices 7130 which are included in the control circuit 80 areformed on the silicon layer 713.

The silicon dioxide layer 714 is disposed on the silicon layer 713, andis used as a wiring forming layer. In the silicon dioxide layer 714,wiring for connecting the control circuit 80 and the switching circuits51 and 52, which are formed on the silicon layer 713, to electrodes 716,which are formed on a surface of the silicon nitride layer 715, isformed. This wiring includes multiple interconnect layers (notillustrated), and multiple via electrodes 7140 which connect theinterconnect layers to each other. The interconnect layers and the viaelectrodes 7140 are formed, for example, of copper or aluminum.

The silicon nitride layer 715 is disposed on the silicon dioxide layer714, and is used as a passivation layer. The electrodes 716 are formedas a redistribution layer on a part of a surface of the silicon nitridelayer 715. The second base 72 and the low thermal conductive member 73are joined to another part of the surface of the silicon nitride layer715.

The electrodes 716 are joined to electrodes (not illustrated), which aredisposed on the module substrate 90, with the electrodes 717 interposedin between. The surfaces of the electrodes 716 are coated by a resinlayer 718 which is an insulating film.

The electrodes 717 are exemplary first electrodes. Each of theelectrodes 717 is an electrode which protrudes from the first base 71toward the principal surface 90 a of the module substrate 90, and isjoined, at its leading end, to the principal surface 90 a. Each of theelectrodes 717 has a columnar conductor 717 a and a bump electrode 717b. The bump electrode 717 b is joined to an electrode (not illustrated)disposed on the principal surface 90 a of the module substrate 90.

The first base 71 is not limited to the configuration in FIG. 4 . Forexample, the first base 71 does not necessarily include one or some ofthe layers on the silicon substrate 711.

1.3.2 The Configuration of the Second Base 72

The second base 72 will be described. At least a part of the second base72 is formed of a second semiconductor material having a thermalconductivity lower than the first semiconductor material. The secondsemiconductor material is gallium arsenide. The second semiconductormaterial is not limited to gallium arsenide. For example, the secondsemiconductor material may be a material containing, as the maincomponent, any of gallium arsenide, aluminum arsenide, indium arsenide,indium phosphide, gallium phosphide, indium antimonide, gallium nitride,indium nitride, aluminum nitride, silicon germanium, silicon carbide,gallium oxide (III), and gallium bismuth (GaBi), or a materialcontaining, as the main component, a multicomponent mixed-crystalmaterial composed of more than one of these materials. The secondsemiconductor material is not limited to these.

The power amplifier circuit 11 is formed in the second base 72.Specifically, multiple circuit devices 721, as well as electrodes (notillustrated) for applying voltages to the circuit devices 721 orelectrodes (not illustrated) for supplying currents, are formed in thesecond base 72. The circuit devices 721 form, for example, aheterojunction bipolar transistor (HBT) in which multiple unittransistors are connected to each other in parallel, and are included inthe power amplifier circuit 11.

As illustrated in FIG. 5 , the second base 72 has surfaces 72 a and 72 bwhich are opposite to each other. The surfaces 72 a and 72 b areexemplary third and fourth surfaces, respectively. An electrode 724 isdisposed on the surface 72 b.

The second base 72 includes a semiconductor layer 72A, an epitaxiallayer 72B formed on a surface of the semiconductor layer 72A, and thecircuit devices 721, and electrodes 722 and 723. The semiconductor layer72A is formed of the second semiconductor material, and is joined to thesilicon nitride layer 715 of the first base 71. The semiconductor layer72A is, for example, a GaAs layer. Each circuit device 721 has acollector layer 721C, a base layer 721B, and an emitter layer 721E. Thecollector layer 721C, the base layer 721B, and the emitter layer 721Eare laminated on the epitaxial layer 72B in this sequence. That is, ineach circuit device 721, the collector layer 721C, the base layer 721B,and the emitter layer 721E are laminated in this sequence from the firstbase 71 side.

For example, the collector layer 721C is formed of n-gallium arsenide.The base layer 721B is formed of p-gallium arsenide. The emitter layer721E is formed of n-indium gallium phosphorus (InGaP). The emitter layer721E is joined to an electrode 723 with an electrode 722 which isinterposed in between and which is formed on the surface of the secondbase 72. The electrode 723 is joined to the principal surface 90 a ofthe module substrate 90 with the electrode 724 interposed in between.

The electrode 724, which is an exemplary second electrode, protrudesfrom the second base 72 toward the principal surface 90 a of the modulesubstrate 90, and is joined, at its leading end, to the principalsurface 90 a. The electrode 724 functions as a thermal-radiation pathfor the heat generated by the power amplifier circuit 11. The electrode724 has a columnar conductor 724 a and a bump electrode 724 b. The bumpelectrode 724 b is joined to an electrode (not illustrated) disposed onthe principal surface 90 a of the module substrate 90.

The configuration of the second base 72 is not limited to that in FIGS.4 and 5 .

1.3.3 The Configuration of the Low Thermal Conductive Member 73

The low thermal conductive member 73 will be described. At least a partof the low thermal conductive member 73 is formed of a low thermalconductive material having a thermal conductivity lower than the secondsemiconductor material. As the low thermal conductive material, glass, asynthetic high polymer, and the like may be used. The synthetic highpolymer may be epoxy resin, and may be another synthetic resin orsynthetic rubber.

The low thermal conductive member 73 is disposed between electriccircuits (for example, the control circuit 80 or the switching circuit51 or 52), which are formed in the first base 71, and the poweramplifier circuit 11, which is formed in the second base 72. In thepresent embodiment, the low thermal conductive member 73 is disposed onthe surface 71 b of the first base 71, and is disposed between thecontrol circuit 80 and the power amplifier circuit 11 in cross-sectionalview. The layout of the low thermal conductive member 73 is not limitedto the layout illustrated in FIG. 4 . For example, the low thermalconductive member 73 may be disposed in the first base 71.

The low thermal conductive member 73 has surfaces 73 a and 73 b. Thesurface 73 a is in contact with the surface 71 b of the first base 71. Apart of the surface 73 b is in contact with the surface 72 a of thesecond base 72.

The shape of the low thermal conductive member 73 is not limited to asheet-like shape. For example, the low thermal conductive member 73 maybe shaped like a block. In addition, the low thermal conductive member73 may include multiple layers. In this case, the low thermal conductivemember 73 may have any configuration as long as at least one of thelayers is formed of the low thermal conductive material.

1.3.4 The Circuit Layout in the Integrated Circuit 70

The circuit layout in the integrated circuit 70 in plan view will bedescribed by referring to FIG. 6 .

As illustrated in FIG. 6 , a part of the low thermal conductive member73 overlaps a part of each of the electric circuits (the control circuit80 and the switching circuits 51 and 52), which are formed in the firstbase 71, in plan view. Further, another part of the low thermalconductive member 73 overlaps a part of the power amplifier circuit 11in plan view.

The circuit layout in the integrated circuit 70, which is illustrated inFIG. 6 , is merely exemplary, and the circuit layout is not limited tothis layout. For example, the low thermal conductive member 73 does notnecessarily overlap the power amplifier circuit 11 and/or, for example,the control circuit 80 in plan view.

1.4 Effects and the Like

As described above, the integrated circuit 70 according to the presentembodiment includes the first base 71, which has at least a part formedof the first semiconductor material and which includes an electriccircuit(s) (for example, the control circuit 80 or the switching circuit51 or 52), the second base 72, which has at least a part formed of thesecond semiconductor material having a thermal conductivity lower thanthe first semiconductor material and which includes the power amplifiercircuit 11, and the low thermal conductive member 73, which has at leasta part formed of the low thermal conductive material having a thermalconductivity lower than the second semiconductor material and which isdisposed between the electric circuit(s) and the power amplifier circuit11. At least a part of the first base 71 overlaps at least a part of thesecond base 72 in plan view.

According to this configuration, the first base 71, in which theelectric circuit(s) is formed, overlaps the second base 72, in which thepower amplifier circuit 11 is formed, in plan view. Thus, the integratedcircuit 70 achieves the contribution to a reduction in size of theradio-frequency module 1. Further, the heat generated by the poweramplifier circuit 11 formed in the second base 72 may be discharged tothe first base 71 which is formed of the first semiconductor materialhaving a thermal conductivity higher than the second semiconductormaterial of which the second base 72 is formed. In this state, the lowthermal conductive member 73, which has a thermal conductivity lowerthan the second semiconductor material, is disposed between the poweramplifier circuit 11 and the electric circuit(s). This achieves thesuppression of the heat transfer from the power amplifier circuit 11 tothe electric circuit(s), and achieves the suppression of the degradationof the characteristics of the electric circuit(s) due to the heat.

In addition, for example, in the integrated circuit 70 according to thepresent embodiment, at least a part of the low thermal conductive member73 may overlap at least a part of each of the electric circuit(s) inplan view

According to this configuration, the low thermal conductive member 73may effectively suppress the heat transfer from the power amplifiercircuit 11 to the electric circuit(s), and may suppress the degradationof the characteristics of the electric circuit(s) due to the heat.

In addition, for example, in the integrated circuit 70 according to thepresent embodiment, at least a part of the low thermal conductive member73 may overlap at least a part of the power amplifier circuit 11 in planview.

According to this configuration, the low thermal conductive member 73may effectively suppress the heat transfer from the power amplifiercircuit 11 to the electric circuit(s), and may suppress the degradationof the characteristics of the electric circuit(s) due to the heat.

In addition, for example, in the integrated circuit 70 according to thepresent embodiment, the low thermal conductive member 73 may be shapedlike a sheet.

According to this configuration, the low thermal conductive member 73enables a heat-transfer path from the power amplifier circuit 11 to theelectric circuit(s) to be blocked widely. Thus, the low thermalconductive member 73 may effectively suppress the heat transfer from thepower amplifier circuit 11 to the electric circuit(s), and may suppressthe degradation of the characteristics of the electric circuit(s) due tothe heat.

In addition, for example, in the integrated circuit 70 according to thepresent embodiment, the electric circuit(s) may include at least one ofthe following circuits: the control circuit 80 which controls the poweramplifier circuit 11; the switching circuit 51 which is connected to theoutput end of the power amplifier circuit 11; and the switching circuit52 which is connected to the input end of the power amplifier circuit11.

According to this configuration, at least one of the circuits, thecontrol circuit 80 and the switching circuits 51 and 52 which areconnected to the power amplifier circuit 11 formed in the second base72, is formed in the first base 71, achieving a reduction of the wiringlength between the power amplifier circuit 11 and at least one of thecircuits, the control circuit 80 and the switching circuits 51 and 52.This achieves a reduction of influence of digital noise due to a controlsignal, and achieves a reduction of wiring loss and mismatching loss dueto the stray capacitance of wiring.

In addition, for example, in the integrated circuit 70 according to thepresent embodiment, the first base 71 may have the surface 71 a, thesurface 71 b, which is on the opposite side of the surface 71 a andwhich faces the second base 72, and the electrodes 717, which aredisposed on the surface 71 b.

According to this configuration, the heat in the first base 71 may bedischarged to the module substrate 90 through the electrodes 717,achieving the improvement of the heat dissipation of the integratedcircuit 70.

In addition, for example, in the integrated circuit 70 according to thepresent embodiment, the second base 72 may have the surface 72 a, whichfaces the first base 71, the surface 72 b, which is on the opposite sideof the surface 72 a, and the electrode 724, which is disposed on thesurface 72 b.

According to this configuration, the heat may be discharged from thesurface 72 b of the second base 72 through the electrode 724 to themodule substrate 90, achieving the improvement of the heat dissipationof the integrated circuit 70.

In addition, for example, in the integrated circuit 70 according to thepresent embodiment, the power amplifier circuit 11 may include thecircuit devices 721, each of which has the collector layer 721C, thebase layer 721B, and the emitter layer 721E. The collector layer 721C,the base layer 721B, and the emitter layer 721E may be laminated in thissequence from the first base 71 side.

According to this configuration, wiring, to which each of the collectorlayer 721C, the base layer 721B, and the emitter layer 721E isconnected, may be easily made in a manufacturing process. In addition,the area of the collector layer 721C is larger than the area of each ofthe base layer 721B and the emitter layer 721E in plan view. Therefore,joining the collector layer 721C to the first base 71 enables the jointarea to be increased compared with the case in which the base layer 721Bor the emitter layer 721E is joined to the first base 71. As a result,the joint between the first base 71 and the second base 72 isstrengthened, achieving the suppression of the state in which the secondbase 72 peels off from the first base 71.

The integrated circuit 70 according to the present embodiment includesthe first base 71, which has at least a part formed of silicon orgallium nitride and which includes an electric circuit(s) (for example,the control circuit 80 or the switching circuit 51 or 52), the secondbase 72, which has at least a part formed of gallium arsenide or silicongermanium and which includes the power amplifier circuit 11, and the lowthermal conductive member 73, which has at least a part formed of glassor epoxy resin and which is disposed between the electric circuit(s) andthe power amplifier circuit 11. At least a part of the first base 71overlaps at least a part of the second base 72 in plan view.

According to this configuration, the first base 71, in which theelectric circuit(s) are formed, overlaps the second base 72, in whichthe power amplifier circuit 11 is formed, in plan view. Thus, theintegrated circuit 70 achieves the contribution to a reduction in sizeof the radio-frequency module 1. Further, the heat generated by thepower amplifier circuit 11 formed in the second base 72 may bedischarged to the first base 71 which is formed of silicon or galliumnitride having a thermal conductivity higher than gallium arsenide orsilicon germanium of which the second base 72 is formed. In this state,the low thermal conductive member 73, which is formed of glass or epoxyresin having a thermal conductivity lower than the second semiconductormaterial, is disposed between the power amplifier circuit 11 and theelectric circuit(s). This achieves the suppression of the heat transferfrom the power amplifier circuit 11 to the electric circuit(s), andachieves the suppression of the degradation of the characteristics ofthe electric circuit(s) due to the heat.

The radio-frequency module 1 according to the present embodimentincludes the module substrate 90, having the principal surface 90 a, andthe integrated circuit 70 disposed on the principal surface 90 a. Thefirst base 71 is joined to the principal surface 90 a with theelectrodes 717 interposed in between. The second base 72 is joined tothe principal surface 90 a with the electrode 724 interposed in between.

According to this configuration, the heat generated by the poweramplifier circuit 11 formed in the second base 72 may be effectivelydischarged to the module substrate 90 through the first base 71, whichis formed of the first semiconductor material having a thermalconductivity higher than the second semiconductor material of which thesecond base 72 is formed, and the electrodes 717. In this state, the lowthermal conductive member 73, having a low thermal conductivity, isdisposed between the electric circuit(s) and the power amplifier circuit11. This achieves the suppression of the amount of the heat transferfrom the power amplifier circuit 11 to the electric circuit(s), andachieves the suppression of the degradation of the characteristics ofthe electric circuit(s) due to the heat.

The communication device 5 according to the present embodiment includesthe RFIC 3, which processes radio-frequency signals, and theradio-frequency module 1, which transports radio-frequency signalsbetween the RFIC 3 and the antenna 2.

According to this configuration, the communication device 5 may havesubstantially the same effects as those of the radio-frequency module 1.

Modified Example

A modified example will be described. The present modified example ismainly different from the embodiment, described above, in that, insteadof the low thermal conductive member, a hollow space is used. Thepresent modified example will be described below by focusing on pointsdifferent from those in the embodiment described above.

The circuit configuration diagram, the plan view, and thecross-sectional view of the radio-frequency module 1 according to thepresent modified example are substantially the same as those of theradio-frequency module 1 according to the embodiment described above,and will be neither illustrated nor described. The configuration of anintegrated circuit 70A according to the present modified example will bedescribed by referring to FIG. 7 .

FIG. 7 is a partial cross-sectional view of the radio-frequency module 1according to the modified example. Specifically, FIG. 7 is an enlargedcross-sectional view of the integrated circuit 70A. In FIG. 7 , not allthe wiring and electrodes are illustrated.

The integrated circuit 70A has a hollow space 73A instead of the lowthermal conductive member 73. The hollow space 73A is a space which isformed in the first base 71 and which has a thermal conductivity lowerthan the second base 72. In the present modified example, the hollowspace 73A is disposed between the control circuit 80 and the poweramplifier circuit 11 in cross-sectional view.

The hollow space 73A is different from bubbles which may be uniformly orrandomly inserted in the first base 71, and is a hollow which isintentionally formed in a predetermined shape. Therefore, the hollowspace 73A may have a non-spherical shape. In FIG. 7 , the hollow space73A spreads in a sheet-like shape along the xy plane in the first base71. A non-spherical shape means a shape which is not spherical. Thelayout and shape of the hollow space 73A are not limited to those inFIG. 7 .

The layout of the hollow space 73A in plan view is substantially thesame as that of the low thermal conductive member 73 according to theembodiment described above, and will be neither illustrated nordescribed.

As described above, the integrated circuit 70A according to the presentmodified example includes the first base 71, which has at least a partformed of the first semiconductor material and which includes anelectric circuit(s) (for example, the control circuit 80 or theswitching circuit 51 or 52), and the second base 72, which has at leasta part formed of the second semiconductor material having a thermalconductivity lower than the first semiconductor material and whichincludes the power amplifier circuit 11. The hollow space 73A, which islocated between the electric circuit(s) and the power amplifier circuit11, is formed inside the first base 71. At least a part of the firstbase 71 overlaps at least a part of the second base 72 in plan view.

According to this configuration, the first base 71, in which theelectric circuit(s) are formed, overlaps the second base 72, in whichthe power amplifier circuit 11 is formed, in plan view. Thus, theintegrated circuit 70 achieves the contribution to a reduction in sizeof the radio-frequency module 1. Further, the heat generated by thepower amplifier circuit 11 formed in the second base 72 may bedischarged to the first base 71 which is formed of the firstsemiconductor material having a thermal conductivity higher than thesecond semiconductor material of which the second base 72 is formed. Inthis state, the hollow space 73A is disposed between the power amplifiercircuit 11 and the electric circuit(s). This achieves the suppression ofthe heat transfer from the power amplifier circuit 11 to the electriccircuit(s), and achieves the suppression of the degradation of thecharacteristics of the electric circuit(s) due to the heat.

In addition, for example, in the integrated circuit 70A according to thepresent modified example, at least a part of the hollow space 73A mayoverlap at least a part of each of the electric circuit(s) in plan view.

According to this configuration, the hollow space 73A may effectivelysuppress the heat transfer from the power amplifier circuit 11 to theelectric circuit(s), and may suppress the degradation of thecharacteristics of the electric circuit(s) due to the heat.

In addition, for example, in the integrated circuit 70A according to thepresent modified example, at least a part of the hollow space 73A mayoverlap at least a part of the power amplifier circuit 11 in plan view.

According to this configuration, the hollow space 73A may effectivelysuppress the heat transfer from the power amplifier circuit 11 to theelectric circuit(s), and may suppress the degradation of thecharacteristics of the electric circuit(s) due to the heat.

In addition, for example, in the integrated circuit 70A according to thepresent modified example, the hollow space 73A may have a non-sphericalshape.

According to this configuration, the shape of the hollow space 73A maybe non-spherical. A shape appropriate for the layout of the poweramplifier circuit 11 and the electric circuit(s) may be employed. Thisachieves the effective suppression of the heat transfer from the poweramplifier circuit 11 to the electric circuit(s), and achieves thesuppression of the degradation of the characteristics of the electriccircuit(s) due to the heat.

In addition, for example, in the integrated circuit 70A according to thepresent modified example, the hollow space 73A may spread in asheet-like shape in the first base 71.

According to this configuration, a heat-transfer path from the poweramplifier circuit 11 to the electric circuit(s) may be blocked widely.This achieves the effective suppression of the heat transfer from thepower amplifier circuit 11 to the electric circuit(s), and achieves thesuppression of the degradation of the characteristics of the electriccircuit(s) due to the heat.

In addition, for example, in the integrated circuit 70A according to thepresent modified example, the electric circuit(s) may include at leastone of the following circuits: the control circuit 80 which controls thepower amplifier circuit 11; the switching circuit 51 which is connectedto the output end of the power amplifier circuit 11; and the switchingcircuit 52 which is connected to the input end of the power amplifiercircuit 11.

According to this configuration, at least one of the circuits, thecontrol circuit 80 and the switching circuits 51 and 52 which areconnected to the power amplifier circuit 11 formed in the second base72, is formed in the first base 71. Thus, the wiring length between thepower amplifier circuit 11 and the at least one of the circuits, thecontrol circuit 80 and the switching circuits 51 and 52, may bedecreased. This achieves a reduction of influence of digital noise dueto a control signal, and achieves a reduction of wiring loss andmismatching loss due to the stray capacitance of wiring.

In addition, for example, in the integrated circuit 70A according to thepresent modified example, the first base 71 may have the surface 71 a,the surface 71 b, which is on the opposite side of the surface 71 a andwhich faces the second base 72, and the electrodes 717, which aredisposed on the surface 71 b.

According to this configuration, the heat in the first base 71 may bedischarged to the module substrate 90 through the electrodes 717,achieving the improvement of the heat dissipation of the integratedcircuit 70A.

In addition, for example, in the integrated circuit 70A according to thepresent modified example, the second base 72 may have the surface 72 a,which faces the first base 71, the surface 72 b, which is on theopposite side of the surface 72 a, and the electrode 724, which isdisposed on the surface 72 b.

According to this configuration, the heat may be discharged from thesurface 72 b of the second base 72 through the electrode 724 to themodule substrate 90, achieving the improvement of the heat dissipationof the integrated circuit 70A.

In addition, for example, in the integrated circuit 70A according to thepresent modified example, the power amplifier circuit 11 may include thecircuit devices 721, each of which has the collector layer 721C, thebase layer 721B, and the emitter layer 721E. The collector layer 721C,the base layer 721B, and the emitter layer 721E may be laminated in thissequence from the first base 71 side.

According to this configuration, wiring, to which each of the collectorlayer 721C, the base layer 721B, and the emitter layer 721E isconnected, may be easily made in a manufacturing process. In addition,the area of the collector layer 721C is larger than the area of each ofthe base layer 721B and the emitter layer 721E in plan view. Therefore,joining the collector layer 721C to the first base 71 enables the jointarea to be increased compared with the case in which the base layer 721Bor the emitter layer 721E is joined to the first base 71. As a result,the joint between the first base 71 and the second base 72 isstrengthened, achieving the suppression of the state in which the secondbase 72 peels off from the first base 71.

As described above, the integrated circuit 70A according to the presentmodified example includes the first base 71, which has at least a partformed of silicon or gallium nitride and which includes an electriccircuit(s) (for example, the control circuit 80 or the switching circuit51 or 52), and the second base 72, which has at least a part formed ofgallium arsenide or silicon germanium and which includes the poweramplifier circuit 11. The hollow space 73A, which is located between theelectric circuit(s) and the power amplifier circuit 11, is formed insidethe first base 71. At least a part of the first base 71 overlaps atleast a part of the second base 72 in plan view.

According to this configuration, the first base 71, in which electriccircuits are formed, overlaps the second base 72, in which the poweramplifier circuit 11 is formed, in plan view. Thus, the integratedcircuit 70A achieves the contribution to a reduction in size of theradio-frequency module 1. Further, the heat generated by the poweramplifier circuit 11 formed in the second base 72 may be discharged tothe first base 71 which is formed of silicon or gallium nitride having athermal conductivity higher than gallium arsenide or silicon germaniumof which the second base 72 is formed. In this state, the hollow space73A is disposed between the power amplifier circuit 11 and the electriccircuit(s). This achieves the suppression of the heat transfer from thepower amplifier circuit 11 to the electric circuit(s), and achieves thesuppression of the degradation of the characteristics of the electriccircuit(s) due to the heat.

The radio-frequency module 1 according to the present modified exampleincludes the module substrate 90, having the principal surface 90 a, andthe integrated circuit 70A disposed on the principal surface 90 a. Thefirst base 71 is joined to the principal surface 90 a with theelectrodes 717 interposed in between. The second base 72 is joined tothe principal surface 90 a with the electrode 724 interposed in between.

According to this configuration, the heat generated by the poweramplifier circuit 11 formed in the second base 72 may be effectivelydischarged to the module substrate 90 through the first base 71, whichis formed of the first semiconductor material having a thermalconductivity higher than the second semiconductor material of which thesecond base 72 is formed, and the electrodes 717. In this state, thehollow space 73A is formed between the electric circuit(s) and the poweramplifier circuit 11. This achieves the suppression of the amount of theheat transfer from the power amplifier circuit 11 to the electriccircuit(s), and achieves the suppression of the degradation of thecharacteristics of the electric circuit(s) due to the heat.

Other Embodiments

An integrated circuit and a radio-frequency module which are provided bythe present disclosure are described on the basis of the embodiment. Theintegrated circuit and the radio-frequency module, which are provided bythe present disclosure, are not limited to the embodiment describedabove. Other embodiments, which are embodied by combining any componentsin the embodiment, modified examples, which are obtained by making, onthe embodiment, various changes conceived by those skilled in the artwithout departing from the gist of the present disclosure, and variousdevices, in which the radio-frequency module is built, are alsoencompassed in the present disclosure.

For example, in the embodiment and the modified example described above,the radio-frequency module 1 is compatible with FDD bands. However, thepresent disclosure is not limited to this. For example, theradio-frequency module 1 may be compatible with TDD (Time DivisionDuplex) bands, or may be compatible with both FDD bands and TDD bands.In this case, the radio-frequency module 1 may have any configuration aslong as the radio-frequency module 1 includes a filter circuit having apassband including a TDD band, and a switching circuit which switchesbetween transmission and reception.

INDUSTRIAL APPLICABILITY

The present disclosure may be widely used as a radio-frequency module,which is disposed in a front-end unit, in communication devices such asa cellular phone.

-   1 radio-frequency module-   2 antenna-   3 RFIC-   4 BBIC-   5 communication device-   11 power amplifier circuit-   20, 70, 70A integrated circuit-   21 low-noise amplifier circuit-   41, 42, 43, 44 impedance matching circuit-   51, 52, 53, 54, 55 switching circuit-   61, 62 duplexer circuit-   61R, 62R receive-filter circuit-   61T, 62T transmit-filter circuit-   71 first base-   71 a, 71 b, 72 a, 72 b, 73 a, 73 b surface-   72 second base-   72A semiconductor layer-   72B epitaxial layer-   73 low thermal conductive member-   73A hollow space-   80 control circuit-   90 module substrate-   90 a, 90 b principal surface-   91 resin member-   92 shield electrode layer-   100 antenna connection terminal-   111, 112 radio-frequency input terminal-   121, 122 radio-frequency output terminal-   130 control terminal-   150 external connection terminal-   711 silicon substrate-   712, 714 silicon dioxide layer-   713 silicon layer-   715 silicon nitride layer-   716, 717, 722, 723, 724 electrode-   717 a, 724 a columnar conductor-   717 b, 724 b bump electrode-   718 resin layer-   721, 7130 circuit device-   721B base layer-   721C collector layer-   721E emitter layer-   7140 via electrode

1. An integrated circuit comprising: a first base including an electriccircuit, wherein at least a part of the first base is formed of a firstsemiconductor material having a first thermal conductivity; a secondbase including a power amplifier circuit, wherein at least a part of thesecond base is formed of a second semiconductor material having a secondthermal conductivity lower than the first thermal conductivity; and alow thermal conductive member disposed between the electric circuit andthe power amplifier circuit, wherein at least a part of the low thermalconductive member is formed of a low thermal conductive material havinga third thermal conductivity lower than the second thermal conductivity,wherein at least a part of the first base overlaps at least a part ofthe second base in plan view.
 2. The integrated circuit according toclaim 1, wherein at least a part of the low thermal conductive memberoverlaps at least a part of the electric circuit in plan view.
 3. Theintegrated circuit according to claim 1, wherein at least a part of thelow thermal conductive member overlaps at least a part of the poweramplifier circuit in plan view.
 4. The integrated circuit according toclaim 3, wherein the low thermal conductive member is shaped like asheet.
 5. The integrated circuit according to claim 1, wherein theelectric circuit comprises at least one of a control circuit, a firstswitching circuit, and a second switching circuit, the control circuitcontrolling the power amplifier circuit, the first switching circuitbeing connected to an output end of the power amplifier circuit, thesecond switching circuit being connected to an input end of the poweramplifier circuit.
 6. The integrated circuit according to claim 1,wherein the first base has a first surface, a second surface being on anopposite side of the first surface and facing the second base, and afirst electrode disposed on the second surface.
 7. The integratedcircuit according to claim 1, wherein the second base has a thirdsurface facing the first base, a fourth surface being on an oppositeside of the third surface, and a second electrode disposed on the fourthsurface.
 8. The integrated circuit according to claim 1, wherein thepower amplifier circuit includes a circuit device having a collectorlayer, a base layer, and an emitter layer, and wherein the collectorlayer, the base layer, and the emitter layer are laminated in thissequence from a side of the first base.
 9. An integrated circuitcomprising: a first base including an electric circuit, wherein at leasta part of the first base is formed of silicon or gallium nitride; asecond base including a power amplifier circuit, wherein at least a partof the second base is formed of gallium arsenide or silicon germanium;and a low thermal conductive member disposed between the electriccircuit and the power amplifier circuit, wherein at least a part of thelow thermal conductive member is formed of glass or epoxy resin, whereinat least a part of the first base overlaps at least a part of the secondbase in plan view.
 10. An integrated circuit comprising: a first baseincluding an electric circuit, wherein at least a part of the first baseis formed of a first semiconductor material having a first thermalconductivity; and a second base including a power amplifier circuit,wherein at least a part of the second base is formed of a secondsemiconductor material having a second thermal conductivity lower thanthe first thermal conductivity, wherein a hollow space is providedinside the first base, the hollow space being located between theelectric circuit and the power amplifier circuit, and wherein at least apart of the first base overlaps at least a part of the second base inplan view.
 11. The integrated circuit according to claim 10, wherein atleast a part of the hollow space overlaps at least a part of theelectric circuit in plan view.
 12. The integrated circuit according toclaim 10, wherein at least a part of the hollow space overlaps at leasta part of the power amplifier circuit in plan view.
 13. The integratedcircuit according to claim 10, wherein the hollow space has anon-spherical shape.
 14. The integrated circuit according to claim 13,wherein the hollow space spreads in a sheet-like shape in the firstbase.
 15. The integrated circuit according to claim 10, wherein theelectric circuit comprises at least one of a control circuit, a firstswitching circuit, and a second switching circuit, the control circuitcontrolling the power amplifier circuit, the first switching circuitbeing connected to an output end of the power amplifier circuit, thesecond switching circuit being connected to an input end of the poweramplifier circuit.
 16. The integrated circuit according to claim 10,wherein the first base has a first surface, a second surface being on anopposite side of the first surface and facing the second base, and afirst electrode disposed on the second surface.
 17. The integratedcircuit according to claim 10, wherein the second base has a thirdsurface facing the first base, a fourth surface being on an oppositeside of the third surface, and a second electrode disposed on the fourthsurface.
 18. The integrated circuit according to claim 10, wherein thepower amplifier circuit includes a circuit device having a collectorlayer, a base layer, and an emitter layer, and wherein the collectorlayer, the base layer, and the emitter layer are laminated in thissequence from the first base side.
 19. An integrated circuit comprising:a first base including an electric circuit, wherein at least a part ofthe first base is formed of silicon or gallium nitride; and a secondbase including a power amplifier circuit, wherein at least a part of thesecond base is formed of gallium arsenide or silicon germanium, whereina hollow space is provided inside the first base, the hollow space beinglocated between the electric circuit and the power amplifier circuit,and wherein at least a part of the first base overlaps at least a partof the second base in plan view.
 20. A radio-frequency modulecomprising: the integrated circuit according to claim 1; and a modulesubstrate having a principal surface on which the integrated circuit isdisposed, wherein the first base is joined to the principal surface witha first electrode interposed in between, and wherein the second base isjoined to the principal surface with a second electrode interposed inbetween.